Question: Simplify the following expression: $n = \dfrac{5}{r} \div \dfrac{5}{4r}$
Explanation: Dividing by an expression is the same as multiplying by its inverse. $n = \dfrac{5}{r} \times \dfrac{4r}{5}$ When multiplying fractions, we multiply the numerators and the denominators. $n = \dfrac{ 5 \times 4r } { r \times 5}$ $n = \dfrac{20r}{5r}$ Simplify: $n = \dfrac{4}{1}$